Medical Moment: Prenatal Vitamin with Iodine?

08 Jan Medical Moment: Prenatal Vitamin with Iodine?

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Dr. Heather Linder

Dr. Heather Linder answers this week’s question: Should I be taking a prenatal vitamin with iodine while I am pregnant or breastfeeding?

Many pregnant and breast-feeding women are deficient in iodine. Adequate iodine is needed to produce thyroid hormone, which is required for healthy brain development in infants and children. Iodine deficiency in pregnancy can negatively impact normal brain development in the infant. According to the World Health Organization (WHO), iodine deficiency worldwide is the leading cause of “preventable mental handicap,” with an average 12 point reduction in IQ of children born to severely iodine deficient mothers.

What causes iodine deficiency?

Iodine deficiency is less common in the United States, but recent studies show that about 30% of pregnant women may be iodine deficient. The most common source of iodine in the American diet is iodized salt. The increase in iodine deficiency in the US has been linked to the increased consumption of processed foods and sea salt, neither of which contain iodized salt. In addition, women who follow a vegan diet may be at risk since they do not eat dairy or fish which are natural sources of iodine in the diet. Environmental pollutants such as nitrate (found in some drinking water and some leafy and root vegetables), thiocyanate (found in tobacco smoke and some cruciferous vegetables), and perchlorate (found in 4% of US public drinking water) can also contribute to iodine deficiency as these chemicals prevent iodine uptake by the thyroid gland.

How much iodine is recommended?

The American Thyroid Association and the Institute of Medicine recommend that lactating women require 290 micrograms of iodide and pregnant women require 220 micrograms of iodide daily. In general, this requires taking a supplement of 150 micrograms of iodide daily plus additional dietary sources of iodine. However, many of the over-the-counter and prescription prenatal vitamins do not contain any iodine. One study shows that only 28% of prescription prenatal vitamins contain iodine. The American Thyroid Association and the American Academy of Pediatrics recommend that 150 micrograms of iodide are added to all prenatal vitamins, but this has not been enforced by the FDA.

Please read the label of your prenatal vitamin to ensure that it contains at least 150 micrograms of iodide or check with your pharmacist if you are taking a prescription prenatal vitamin.

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